application of nanofiltration and reverse osmosis for tanning wastewater

the aim to achieve in this study is to recover the cr(iii) and process waters used in thewastewaters of chrome tanning operation by membrane process during leather production. in the treatmentalternative contains, cartridge filter, nanofiltration (nf(np10)), nanofiltration nf(xn45) and reverse osmosisro(acm2) membranes. the raw chrome wastewater from the cartridge filter was given to nf(np10)membranes with 3 different pressures (12bar, 16bar, 18bar). in this alternative, the most appropriate pressure is determined as 20 bar and the cod, cr(iii) and ss values were detected as, in order, 65%, 49% and 87% for the removal efficiency. 2,7 times more concentration for cr(iii) was achieved in the nf (xn45) membrane, which was used after nf(np10) membrane and cod, ss, so4-2, na+ and conductivity parameters showed removal efficiencies as, 75%, 89%, 95%, 38% and 16%. the permeate from ro(acm2) membrane was decreased to the discharge criteria’s; (cr(iii):2 mg/l, cod: 200 mg/l). as a result, the investment and the process cost of these membranes are more feasible.